I was having a doubt.. While doing a research, usually when should I use longitudinal and cross-sectional study? Whats d difference between the two & should be used when??
If you want to study the same sample over a period of time for your research, then it is a longitudinal study & at the same time if you want to study different samples, then it is cross-sectional study.
Longitudinal study is commonly carried out in the medical field, say where the same patients are observed over few years for changes. On the other hand, in cross-sectional study multiple populations are studied at a single point in time, say to study the online purchasing behaviour among different sections based on age groups or gender or occupation.
Hope this answers your question.
You can also refer these links for a detailed understanding on longitudinal and cross-sectional study along with some examples.